The invention relates to a drinking vessel, and in particular a drinking vessel such as an infant cup.
A range of infant cups are known, for example of the type generally termed trainer cups, including a cup-like body often including handles for ease of use by a infant, a cover and a drinking spout provided on the cover. The spout can be rigid or flexible. The cup is easier to handle and allows the infant to drink from the cup with less risk of spillage.
Various improvements to infant cups are known. For example U.S. Pat. No. 5,186,347 and GB 2304545 relate to trainer cups including a slit valve membrane fixed at the tip of the spout, which allows liquid to flow when the infant sucks but closes otherwise. As a result the cup is largely spill-proof under normal conditions.
Problems exist with the known arrangements, however. The moulding and fitting of the membranes may be a complex and costly, operation, residue may be trapped where the membrane and spout meet, and because of the typically small orifice at the spout the membrane may be difficult to clean. In addition, the child is often required to suck very hard to open slit valve membranes of this type which can be tiring and offputting for the child. The slit valves are very fragile and can be easily damaged, a particular risk in view of the use of the cup by a child, and the likelihood that a child will be left unattended with it because of its spillproof nature.
Yet further, as liquid is removed from the known cups, a negative pressure may develop in the cup which may make further drinking yet harder and removal of the lid equally difficult. It is difficult to open the valve manually to overcome this problem without damaging it.
A particular problem with valves of the known type arises when fruit juices are drunk from the vesselxe2x80x94in this case the fibres can clog the slit and prevent it from sealing properly, which can give rise to leakage.
The invention is set out in the appended claims.
Embodiments of the invention will now be described, by way of example, with reference to the drawings, of which: